The present invention relates to a tape cassette for use with a recording/reproducing device, and more particularly to such a tape cassette including a cassette case, a pair of rotatable tape reels accommodated in the cassette case for winding a magnetic tape therearound, a mouth section formed between and along the front of the tape reels in the cassette case for receiving a head drum and the like of a recording/reproducing device, and means for allowing pivotal movement of the tape reels to rear corner portions of the cassette, whereby when the tape cassette is loaded into the recording/reproducing device, the tape reels are pivotally moved from an initial position to a retracted position defined at the rear corner portions of the cassette case, thereby expanding the mouth section.
It has been proposed that a pair of tape reels are rotatably accommodated in a cassette case having the same external form as that of a standard tape cassette conventionally standardized so that the tape reels can be pivotally moved between an initial position allowing the compatibility with the standard tape cassette and a retracted position where the tape reels are retracted to rear corner portions of the cassette case for the purpose of adaptation to a dedicated recording/reproducing device. When the tape reels are moved to the retracted position, a mouth section defined between and front of the tape reels can be expanded to allow a head drum and the like to be deeply inserted into the expanded mouth section. Accordingly, the recording/reproducing device dedicated for such a tape cassette can be made compact. Further, the tape cassette can also be applied to another type recording/reproducing device employing a standard tape cassette by restoring the initial position of the tape reels.
However, in such a tape cassette including the movable tape reels, there is a problem such that the positions of the tape reels during the operation are not stabilized because of the fact that the tape reels are movable, causing the generation of vibration or a force providing a deviated side pressure to reel engagement shafts engaging the tape reels, thus hindering stable running of a tape. In particular, in the case where the tape cassette is provided with biasing means for returning the tape reels to the initial position, a return force of the biasing means to restore the initial position is always applied to the tape reels irrespective of the operational condition of the tape cassette. Accordingly, the return force applied to the tape reels undesirably provides a deviated side pressure to the reel engagement shafts.